1. Field of the Invention
The invention relates to article conveyors generally and, more particularly, to conveyors having an article-conveying surface with article-engagement characteristics that can be changed while the conveyor is running.
2. Description of the Related Art
Conveyor belts are used widely to transport articles through plants. During its odyssey through a plant, an article encounters a variety of challenges. For example, the article may need to descend from one level to a lower level or to climb from the lower level to a higher level. To give the article some traction on an incline or to prevent it from sliding out of control down a decline, conveyor belts with rubber or other high friction materials on the conveying surface are used. At other places in the plant, a number of articles must be accumulated because, for example, a downstream process is proceeding more slowly than an upstream process. To prevent the accumulating articles from crushing each other as the conveyor belt continues to move, a belt having rollers providing a low-friction conveying surface is used. The rollers allow the belt to slide past the undersides of the accumulated articles with little backline pressure. Sometimes it is necessary to space the articles from each other. Singulators with a controlled gate are often used to separate conveyed articles from each other. Finally, an article's journey through the plant ends. Often the article is pushed off the side of the belt onto a platform for shipment. A belt with rollers capable of rotating in a direction to aid a side-off transfer is useful in this application.
The response to one challenge confronting the article as it travels through the plant is often incompatible with the other challenges. Consequently, the common solution is to use a series of conveyors each having a conveying surface characteristic suited to overcoming the particular challenge. But this solution requires a number of different-style belts, more belt drive systems, and more plant space to handle the additional feet of belt, drive components, and transfer mechanisms required. Thus, there is a need for a conveyor system that can handle combinations of these conflicting transport requirements of high-friction conveyance, low-friction conveyance, side-off transfer, low backline pressure, and product separation.